The cell coat or glycocalyx, rich in glycoproteins, plays a role in many interactions of cells with their microenvironment and with each other. Indeed, alterations in the composition of the cell coat accompany malignant changes of many cell types including the epithelial cells of the colon. It has been established that cell coat glycoproteins receive some of their carbohydrates in the Golgi apparatus. The cell coat material in the columnar epithelial cells of the asceding colon of the mouse is then transported to the cell surface by vesicles. However, 1) the requirement for normal glycosylation for maintenance of this system is unknown, and 2) the means by which these vesicles are moved to the surface has not been defined. In the current study we will address these two problems by the use of two inhibitory drugs and observe the effects in mouse colon cells. 1) Diazo-oxo norleucine, formerly employed as a cancer chemotherapeutic agent, inhibits formation of carbohydrates that are often the initial sugars attached to proteins, N-acetyl galactosamine and N-acetyl glucosamine. Absence of these carbohydrates would result in a reduction of further glycosylation. The effects of this compound on the cell cat and the organelles involved in its synthetic pathway will be analyzed by electron microscopy and cytochemistry. Several control experiments will ensure that the findings are related to the specific inhibition of glycosylation. 2) Colchicine inhibits intracellular movement associated with microtubules. It is likely that the directed movement of glycoprotein carrying vesicles toward surface membranes is associated in some manner, with microtubuls. However, since the role of these vesicles appears to differ somewhat from secretory vesicles, their interaction with microtubules requires investigation. Using cytochemistry and radioautography at the level of fine structure, we will a) determine whether movement of this type of vesicle is curtailed by interference with microtubules and, if so, b) the effects on cell coat maintenance and turnover when continual replacement of this material is disrupted.